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/*
* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013, 2022, Red Hat, Inc. All rights reserved.
+ * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
#include "gc/shared/locationPrinter.inline.hpp"
#include "gc/shared/memAllocator.hpp"
#include "gc/shared/plab.hpp"
#include "gc/shared/tlab_globals.hpp"
+ #include "gc/shenandoah/shenandoahAgeCensus.hpp"
+ #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp"
+ #include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp"
+ #include "gc/shenandoah/shenandoahAllocRequest.hpp"
#include "gc/shenandoah/shenandoahBarrierSet.hpp"
+ #include "gc/shenandoah/shenandoahCardTable.hpp"
#include "gc/shenandoah/shenandoahClosures.inline.hpp"
#include "gc/shenandoah/shenandoahCollectionSet.hpp"
#include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
#include "gc/shenandoah/shenandoahConcurrentMark.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
#include "gc/shenandoah/shenandoahControlThread.hpp"
+ #include "gc/shenandoah/shenandoahRegulatorThread.hpp"
#include "gc/shenandoah/shenandoahFreeSet.hpp"
+ #include "gc/shenandoah/shenandoahGlobalGeneration.hpp"
#include "gc/shenandoah/shenandoahPhaseTimings.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
#include "gc/shenandoah/shenandoahInitLogger.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
#include "gc/shenandoah/shenandoahMemoryPool.hpp"
#include "gc/shenandoah/shenandoahMetrics.hpp"
#include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
+ #include "gc/shenandoah/shenandoahOldGeneration.hpp"
#include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
#include "gc/shenandoah/shenandoahPacer.inline.hpp"
#include "gc/shenandoah/shenandoahPadding.hpp"
#include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
#include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
#include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
+ #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
#include "gc/shenandoah/shenandoahSTWMark.hpp"
#include "gc/shenandoah/shenandoahUtils.hpp"
#include "gc/shenandoah/shenandoahVerifier.hpp"
#include "gc/shenandoah/shenandoahCodeRoots.hpp"
#include "gc/shenandoah/shenandoahVMOperations.hpp"
#include "gc/shenandoah/shenandoahWorkGroup.hpp"
#include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
+ #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
+ #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
#include "gc/shenandoah/mode/shenandoahIUMode.hpp"
#include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
#include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
+ #include "utilities/globalDefinitions.hpp"
+
#if INCLUDE_JFR
#include "gc/shenandoah/shenandoahJfrSupport.hpp"
#endif
#include "classfile/systemDictionary.hpp"
_num_regions = ShenandoahHeapRegion::region_count();
assert(_num_regions == (max_byte_size / reg_size_bytes),
"Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
_num_regions, max_byte_size, reg_size_bytes);
- // Now we know the number of regions, initialize the heuristics.
- initialize_heuristics();
-
size_t num_committed_regions = init_byte_size / reg_size_bytes;
num_committed_regions = MIN2(num_committed_regions, _num_regions);
assert(num_committed_regions <= _num_regions, "sanity");
_initial_size = num_committed_regions * reg_size_bytes;
// Default to max heap size.
_soft_max_size = _num_regions * reg_size_bytes;
_committed = _initial_size;
+ // Now we know the number of regions and heap sizes, initialize the heuristics.
+ initialize_heuristics_generations();
+
size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
//
if (!_heap_region_special) {
os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
"Cannot commit heap memory");
}
+ BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this, _heap_region));
+
+ //
+ // After reserving the Java heap, create the card table, barriers, and workers, in dependency order
+ //
+ if (mode()->is_generational()) {
+ ShenandoahDirectCardMarkRememberedSet *rs;
+ ShenandoahCardTable* card_table = ShenandoahBarrierSet::barrier_set()->card_table();
+ size_t card_count = card_table->cards_required(heap_rs.size() / HeapWordSize);
+ rs = new ShenandoahDirectCardMarkRememberedSet(ShenandoahBarrierSet::barrier_set()->card_table(), card_count);
+ _card_scan = new ShenandoahScanRemembered<ShenandoahDirectCardMarkRememberedSet>(rs);
+
+ // Age census structure
+ _age_census = new ShenandoahAgeCensus();
+ }
+
+ _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
+ if (_workers == nullptr) {
+ vm_exit_during_initialization("Failed necessary allocation.");
+ } else {
+ _workers->initialize_workers();
+ }
+
+ if (ParallelGCThreads > 1) {
+ _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", ParallelGCThreads);
+ _safepoint_workers->initialize_workers();
+ }
+
//
// Reserve and commit memory for bitmap(s)
//
size_t bitmap_size_orig = ShenandoahMarkBitMap::compute_size(heap_rs.size());
if (!_bitmap_region_special) {
os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
"Cannot commit bitmap memory");
}
- _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
+ _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
if (ShenandoahVerify) {
ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
os::trace_page_sizes_for_requested_size("Verify Bitmap",
bitmap_size_orig, bitmap_page_size,
cset_rs.base(),
cset_rs.size(), cset_rs.page_size());
}
_regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
+ _affiliations = NEW_C_HEAP_ARRAY(uint8_t, _num_regions, mtGC);
_free_set = new ShenandoahFreeSet(this, _num_regions);
{
ShenandoahHeapLocker locker(lock());
+
for (size_t i = 0; i < _num_regions; i++) {
HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
bool is_committed = i < num_committed_regions;
void* loc = region_storage.base() + i * region_align;
assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
_marking_context->initialize_top_at_mark_start(r);
_regions[i] = r;
assert(!collection_set()->is_in(i), "New region should not be in collection set");
+
+ _affiliations[i] = ShenandoahAffiliation::FREE;
}
// Initialize to complete
_marking_context->mark_complete();
+ size_t young_cset_regions, old_cset_regions;
- _free_set->rebuild();
+ // We are initializing free set. We ignore cset region tallies.
+ _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions);
+ _free_set->rebuild(young_cset_regions, old_cset_regions);
}
if (AlwaysPreTouch) {
// For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
// before initialize() below zeroes it with initializing thread. For any given region,
} else {
_pacer = nullptr;
}
_control_thread = new ShenandoahControlThread();
+ _regulator_thread = new ShenandoahRegulatorThread(_control_thread);
- ShenandoahInitLogger::print();
+ print_init_logger();
return JNI_OK;
}
- void ShenandoahHeap::initialize_mode() {
+ void ShenandoahHeap::print_init_logger() const {
+ ShenandoahInitLogger::print();
+ }
+
+ size_t ShenandoahHeap::max_size_for(ShenandoahGeneration* generation) const {
+ switch (generation->type()) {
+ case YOUNG:
+ return _generation_sizer.max_young_size();
+ case OLD:
+ return max_capacity() - _generation_sizer.min_young_size();
+ case GLOBAL_GEN:
+ case GLOBAL_NON_GEN:
+ return max_capacity();
+ default:
+ ShouldNotReachHere();
+ return 0;
+ }
+ }
+
+ size_t ShenandoahHeap::min_size_for(ShenandoahGeneration* generation) const {
+ switch (generation->type()) {
+ case YOUNG:
+ return _generation_sizer.min_young_size();
+ case OLD:
+ return max_capacity() - _generation_sizer.max_young_size();
+ case GLOBAL_GEN:
+ case GLOBAL_NON_GEN:
+ return min_capacity();
+ default:
+ ShouldNotReachHere();
+ return 0;
+ }
+ }
+
+ void ShenandoahHeap::initialize_heuristics_generations() {
if (ShenandoahGCMode != nullptr) {
if (strcmp(ShenandoahGCMode, "satb") == 0) {
_gc_mode = new ShenandoahSATBMode();
} else if (strcmp(ShenandoahGCMode, "iu") == 0) {
_gc_mode = new ShenandoahIUMode();
} else if (strcmp(ShenandoahGCMode, "passive") == 0) {
_gc_mode = new ShenandoahPassiveMode();
+ } else if (strcmp(ShenandoahGCMode, "generational") == 0) {
+ _gc_mode = new ShenandoahGenerationalMode();
} else {
vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
}
} else {
vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
vm_exit_during_initialization(
err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
_gc_mode->name()));
}
- }
- void ShenandoahHeap::initialize_heuristics() {
- assert(_gc_mode != nullptr, "Must be initialized");
- _heuristics = _gc_mode->initialize_heuristics();
+ // Max capacity is the maximum _allowed_ capacity. That is, the maximum allowed capacity
+ // for old would be total heap - minimum capacity of young. This means the sum of the maximum
+ // allowed for old and young could exceed the total heap size. It remains the case that the
+ // _actual_ capacity of young + old = total.
+ _generation_sizer.heap_size_changed(max_capacity());
+ size_t initial_capacity_young = _generation_sizer.max_young_size();
+ size_t max_capacity_young = _generation_sizer.max_young_size();
+ size_t initial_capacity_old = max_capacity() - max_capacity_young;
+ size_t max_capacity_old = max_capacity() - initial_capacity_young;
- if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
- vm_exit_during_initialization(
- err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
- _heuristics->name()));
- }
- if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
- vm_exit_during_initialization(
- err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
- _heuristics->name()));
+ _young_generation = new ShenandoahYoungGeneration(_max_workers, max_capacity_young, initial_capacity_young);
+ _old_generation = new ShenandoahOldGeneration(_max_workers, max_capacity_old, initial_capacity_old);
+ _global_generation = new ShenandoahGlobalGeneration(_gc_mode->is_generational(), _max_workers, max_capacity(), max_capacity());
+ _global_generation->initialize_heuristics(_gc_mode);
+ if (mode()->is_generational()) {
+ _young_generation->initialize_heuristics(_gc_mode);
+ _old_generation->initialize_heuristics(_gc_mode);
}
+ _evac_tracker = new ShenandoahEvacuationTracker(mode()->is_generational());
}
#ifdef _MSC_VER
#pragma warning( push )
#pragma warning( disable:4355 ) // 'this' : used in base member initializer list
#endif
ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
CollectedHeap(),
+ _gc_generation(nullptr),
+ _prepare_for_old_mark(false),
_initial_size(0),
- _used(0),
+ _promotion_potential(0),
_committed(0),
- _bytes_allocated_since_gc_start(0),
- _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
+ _max_workers(MAX3(ConcGCThreads, ParallelGCThreads, 1U)),
_workers(nullptr),
_safepoint_workers(nullptr),
_heap_region_special(false),
_num_regions(0),
_regions(nullptr),
+ _affiliations(nullptr),
_update_refs_iterator(this),
+ _promoted_reserve(0),
+ _old_evac_reserve(0),
+ _old_evac_expended(0),
+ _young_evac_reserve(0),
+ _captured_old_usage(0),
+ _previous_promotion(0),
+ _upgraded_to_full(false),
+ _age_census(nullptr),
+ _has_evacuation_reserve_quantities(false),
+ _cancel_requested_time(0),
+ _young_generation(nullptr),
+ _global_generation(nullptr),
+ _old_generation(nullptr),
_control_thread(nullptr),
+ _regulator_thread(nullptr),
_shenandoah_policy(policy),
- _gc_mode(nullptr),
- _heuristics(nullptr),
_free_set(nullptr),
_pacer(nullptr),
_verifier(nullptr),
_phase_timings(nullptr),
+ _evac_tracker(nullptr),
+ _mmu_tracker(),
+ _generation_sizer(&_mmu_tracker),
_monitoring_support(nullptr),
_memory_pool(nullptr),
+ _young_gen_memory_pool(nullptr),
+ _old_gen_memory_pool(nullptr),
_stw_memory_manager("Shenandoah Pauses"),
_cycle_memory_manager("Shenandoah Cycles"),
_gc_timer(new ConcurrentGCTimer()),
_soft_ref_policy(),
_log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
- _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
+ _old_regions_surplus(0),
+ _old_regions_deficit(0),
_marking_context(nullptr),
_bitmap_size(0),
_bitmap_regions_per_slice(0),
_bitmap_bytes_per_slice(0),
_bitmap_region_special(false),
_aux_bitmap_region_special(false),
_liveness_cache(nullptr),
- _collection_set(nullptr)
+ _collection_set(nullptr),
+ _card_scan(nullptr)
{
- // Initialize GC mode early, so we can adjust barrier support
- initialize_mode();
- BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
-
- _max_workers = MAX2(_max_workers, 1U);
- _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
- if (_workers == nullptr) {
- vm_exit_during_initialization("Failed necessary allocation.");
- } else {
- _workers->initialize_workers();
- }
-
- if (ParallelGCThreads > 1) {
- _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread",
- ParallelGCThreads);
- _safepoint_workers->initialize_workers();
- }
}
#ifdef _MSC_VER
#pragma warning( pop )
#endif
- class ShenandoahResetBitmapTask : public WorkerTask {
- private:
- ShenandoahRegionIterator _regions;
-
- public:
- ShenandoahResetBitmapTask() :
- WorkerTask("Shenandoah Reset Bitmap") {}
-
- void work(uint worker_id) {
- ShenandoahHeapRegion* region = _regions.next();
- ShenandoahHeap* heap = ShenandoahHeap::heap();
- ShenandoahMarkingContext* const ctx = heap->marking_context();
- while (region != nullptr) {
- if (heap->is_bitmap_slice_committed(region)) {
- ctx->clear_bitmap(region);
- }
- region = _regions.next();
- }
- }
- };
-
- void ShenandoahHeap::reset_mark_bitmap() {
- assert_gc_workers(_workers->active_workers());
- mark_incomplete_marking_context();
-
- ShenandoahResetBitmapTask task;
- _workers->run_task(&task);
- }
-
void ShenandoahHeap::print_on(outputStream* st) const {
st->print_cr("Shenandoah Heap");
st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
st->print("Status: ");
if (has_forwarded_objects()) st->print("has forwarded objects, ");
- if (is_concurrent_mark_in_progress()) st->print("marking, ");
+ if (is_concurrent_old_mark_in_progress()) st->print("old marking, ");
+ if (is_concurrent_young_mark_in_progress()) st->print("young marking, ");
if (is_evacuation_in_progress()) st->print("evacuating, ");
if (is_update_refs_in_progress()) st->print("updating refs, ");
if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
if (is_full_gc_in_progress()) st->print("full gc, ");
if (is_full_gc_move_in_progress()) st->print("full gc move, ");
}
};
void ShenandoahHeap::post_initialize() {
CollectedHeap::post_initialize();
+ _mmu_tracker.initialize();
+
MutexLocker ml(Threads_lock);
ShenandoahInitWorkerGCLABClosure init_gclabs;
_workers->threads_do(&init_gclabs);
if (_safepoint_workers != nullptr) {
_safepoint_workers->threads_do(&init_gclabs);
_safepoint_workers->set_initialize_gclab();
}
- _heuristics->initialize();
-
JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
}
+ ShenandoahHeuristics* ShenandoahHeap::heuristics() {
+ return _global_generation->heuristics();
+ }
+
+ ShenandoahOldHeuristics* ShenandoahHeap::old_heuristics() {
+ return (ShenandoahOldHeuristics*) _old_generation->heuristics();
+ }
+
+ ShenandoahYoungHeuristics* ShenandoahHeap::young_heuristics() {
+ return (ShenandoahYoungHeuristics*) _young_generation->heuristics();
+ }
+
+ bool ShenandoahHeap::doing_mixed_evacuations() {
+ return _old_generation->state() == ShenandoahOldGeneration::WAITING_FOR_EVAC;
+ }
+
+ bool ShenandoahHeap::is_old_bitmap_stable() const {
+ return _old_generation->is_mark_complete();
+ }
+
+ bool ShenandoahHeap::is_gc_generation_young() const {
+ return _gc_generation != nullptr && _gc_generation->is_young();
+ }
+
size_t ShenandoahHeap::used() const {
- return Atomic::load(&_used);
+ return global_generation()->used();
}
size_t ShenandoahHeap::committed() const {
return Atomic::load(&_committed);
}
- size_t ShenandoahHeap::available() const {
- return free_set()->available();
- }
-
void ShenandoahHeap::increase_committed(size_t bytes) {
shenandoah_assert_heaplocked_or_safepoint();
_committed += bytes;
}
void ShenandoahHeap::decrease_committed(size_t bytes) {
shenandoah_assert_heaplocked_or_safepoint();
_committed -= bytes;
}
- void ShenandoahHeap::increase_used(size_t bytes) {
- Atomic::add(&_used, bytes, memory_order_relaxed);
+ // For tracking usage based on allocations, it should be the case that:
+ // * The sum of regions::used == heap::used
+ // * The sum of a generation's regions::used == generation::used
+ // * The sum of a generation's humongous regions::free == generation::humongous_waste
+ // These invariants are checked by the verifier on GC safepoints.
+ //
+ // Additional notes:
+ // * When a mutator's allocation request causes a region to be retired, the
+ // free memory left in that region is considered waste. It does not contribute
+ // to the usage, but it _does_ contribute to allocation rate.
+ // * The bottom of a PLAB must be aligned on card size. In some cases this will
+ // require padding in front of the PLAB (a filler object). Because this padding
+ // is included in the region's used memory we include the padding in the usage
+ // accounting as waste.
+ // * Mutator allocations are used to compute an allocation rate. They are also
+ // sent to the Pacer for those purposes.
+ // * There are three sources of waste:
+ // 1. The padding used to align a PLAB on card size
+ // 2. Region's free is less than minimum TLAB size and is retired
+ // 3. The unused portion of memory in the last region of a humongous object
+ void ShenandoahHeap::increase_used(const ShenandoahAllocRequest& req) {
+ size_t actual_bytes = req.actual_size() * HeapWordSize;
+ size_t wasted_bytes = req.waste() * HeapWordSize;
+ ShenandoahGeneration* generation = generation_for(req.affiliation());
+
+ if (req.is_gc_alloc()) {
+ assert(wasted_bytes == 0 || req.type() == ShenandoahAllocRequest::_alloc_plab, "Only PLABs have waste");
+ increase_used(generation, actual_bytes + wasted_bytes);
+ } else {
+ assert(req.is_mutator_alloc(), "Expected mutator alloc here");
+ // padding and actual size both count towards allocation counter
+ generation->increase_allocated(actual_bytes + wasted_bytes);
+
+ // only actual size counts toward usage for mutator allocations
+ increase_used(generation, actual_bytes);
+
+ // notify pacer of both actual size and waste
+ notify_mutator_alloc_words(req.actual_size(), req.waste());
+
+ if (wasted_bytes > 0 && req.actual_size() > ShenandoahHeapRegion::humongous_threshold_words()) {
+ increase_humongous_waste(generation,wasted_bytes);
+ }
+ }
}
- void ShenandoahHeap::set_used(size_t bytes) {
- Atomic::store(&_used, bytes);
+ void ShenandoahHeap::increase_humongous_waste(ShenandoahGeneration* generation, size_t bytes) {
+ generation->increase_humongous_waste(bytes);
+ if (!generation->is_global()) {
+ global_generation()->increase_humongous_waste(bytes);
+ }
}
- void ShenandoahHeap::decrease_used(size_t bytes) {
- assert(used() >= bytes, "never decrease heap size by more than we've left");
- Atomic::sub(&_used, bytes, memory_order_relaxed);
+ void ShenandoahHeap::decrease_humongous_waste(ShenandoahGeneration* generation, size_t bytes) {
+ generation->decrease_humongous_waste(bytes);
+ if (!generation->is_global()) {
+ global_generation()->decrease_humongous_waste(bytes);
+ }
}
- void ShenandoahHeap::increase_allocated(size_t bytes) {
- Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
+ void ShenandoahHeap::increase_used(ShenandoahGeneration* generation, size_t bytes) {
+ generation->increase_used(bytes);
+ if (!generation->is_global()) {
+ global_generation()->increase_used(bytes);
+ }
}
- void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
- size_t bytes = words * HeapWordSize;
- if (!waste) {
- increase_used(bytes);
+ void ShenandoahHeap::decrease_used(ShenandoahGeneration* generation, size_t bytes) {
+ generation->decrease_used(bytes);
+ if (!generation->is_global()) {
+ global_generation()->decrease_used(bytes);
}
- increase_allocated(bytes);
+ }
+
+ void ShenandoahHeap::notify_mutator_alloc_words(size_t words, size_t waste) {
if (ShenandoahPacing) {
control_thread()->pacing_notify_alloc(words);
- if (waste) {
- pacer()->claim_for_alloc(words, true);
+ if (waste > 0) {
+ pacer()->claim_for_alloc(waste, true);
}
}
}
size_t ShenandoahHeap::capacity() const {
size_t ShenandoahHeap::initial_capacity() const {
return _initial_size;
}
- bool ShenandoahHeap::is_in(const void* p) const {
- HeapWord* heap_base = (HeapWord*) base();
- HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
- return p >= heap_base && p < last_region_end;
- }
-
void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
assert (ShenandoahUncommit, "should be enabled");
// Application allocates from the beginning of the heap, and GC allocates at
// the end of it. It is more efficient to uncommit from the end, so that applications
SpinPause(); // allow allocators to take the lock
}
if (count > 0) {
control_thread()->notify_heap_changed();
+ regulator_thread()->notify_heap_changed();
+ }
+ }
+
+ void ShenandoahHeap::handle_old_evacuation(HeapWord* obj, size_t words, bool promotion) {
+ // Only register the copy of the object that won the evacuation race.
+ card_scan()->register_object_without_lock(obj);
+
+ // Mark the entire range of the evacuated object as dirty. At next remembered set scan,
+ // we will clear dirty bits that do not hold interesting pointers. It's more efficient to
+ // do this in batch, in a background GC thread than to try to carefully dirty only cards
+ // that hold interesting pointers right now.
+ card_scan()->mark_range_as_dirty(obj, words);
+
+ if (promotion) {
+ // This evacuation was a promotion, track this as allocation against old gen
+ old_generation()->increase_allocated(words * HeapWordSize);
+ }
+ }
+
+ void ShenandoahHeap::handle_old_evacuation_failure() {
+ if (_old_gen_oom_evac.try_set()) {
+ log_info(gc)("Old gen evac failure.");
+ }
+ }
+
+ void ShenandoahHeap::report_promotion_failure(Thread* thread, size_t size) {
+ // We squelch excessive reports to reduce noise in logs.
+ const size_t MaxReportsPerEpoch = 4;
+ static size_t last_report_epoch = 0;
+ static size_t epoch_report_count = 0;
+
+ size_t promotion_reserve;
+ size_t promotion_expended;
+
+ size_t gc_id = control_thread()->get_gc_id();
+
+ if ((gc_id != last_report_epoch) || (epoch_report_count++ < MaxReportsPerEpoch)) {
+ {
+ // Promotion failures should be very rare. Invest in providing useful diagnostic info.
+ ShenandoahHeapLocker locker(lock());
+ promotion_reserve = get_promoted_reserve();
+ promotion_expended = get_promoted_expended();
+ }
+ PLAB* plab = ShenandoahThreadLocalData::plab(thread);
+ size_t words_remaining = (plab == nullptr)? 0: plab->words_remaining();
+ const char* promote_enabled = ShenandoahThreadLocalData::allow_plab_promotions(thread)? "enabled": "disabled";
+ ShenandoahGeneration* old_gen = old_generation();
+ size_t old_capacity = old_gen->max_capacity();
+ size_t old_usage = old_gen->used();
+ size_t old_free_regions = old_gen->free_unaffiliated_regions();
+
+ log_info(gc, ergo)("Promotion failed, size " SIZE_FORMAT ", has plab? %s, PLAB remaining: " SIZE_FORMAT
+ ", plab promotions %s, promotion reserve: " SIZE_FORMAT ", promotion expended: " SIZE_FORMAT
+ ", old capacity: " SIZE_FORMAT ", old_used: " SIZE_FORMAT ", old unaffiliated regions: " SIZE_FORMAT,
+ size * HeapWordSize, plab == nullptr? "no": "yes",
+ words_remaining * HeapWordSize, promote_enabled, promotion_reserve, promotion_expended,
+ old_capacity, old_usage, old_free_regions);
+
+ if ((gc_id == last_report_epoch) && (epoch_report_count >= MaxReportsPerEpoch)) {
+ log_info(gc, ergo)("Squelching additional promotion failure reports for current epoch");
+ } else if (gc_id != last_report_epoch) {
+ last_report_epoch = gc_id;;
+ epoch_report_count = 1;
+ }
}
}
HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
// New object should fit the GCLAB size
size_t min_size = MAX2(size, PLAB::min_size());
// Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
+
+ // Limit growth of GCLABs to ShenandoahMaxEvacLABRatio * the minimum size. This enables more equitable distribution of
+ // available evacuation buidget between the many threads that are coordinating in the evacuation effort.
+ if (ShenandoahMaxEvacLABRatio > 0) {
+ log_debug(gc, free)("Allocate new gclab: " SIZE_FORMAT ", " SIZE_FORMAT, new_size, PLAB::min_size() * ShenandoahMaxEvacLABRatio);
+ new_size = MIN2(new_size, PLAB::min_size() * ShenandoahMaxEvacLABRatio);
+ }
+
new_size = MIN2(new_size, PLAB::max_size());
new_size = MAX2(new_size, PLAB::min_size());
// Record new heuristic value even if we take any shortcut. This captures
// the case when moderately-sized objects always take a shortcut. At some point,
ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
if (new_size < size) {
// New size still does not fit the object. Fall back to shared allocation.
// This avoids retiring perfectly good GCLABs, when we encounter a large object.
+ log_debug(gc, free)("New gclab size (" SIZE_FORMAT ") is too small for " SIZE_FORMAT, new_size, size);
return nullptr;
}
// Retire current GCLAB, and allocate a new one.
PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
}
gclab->set_buf(gclab_buf, actual_size);
return gclab->allocate(size);
}
+ // Establish a new PLAB and allocate size HeapWords within it.
+ HeapWord* ShenandoahHeap::allocate_from_plab_slow(Thread* thread, size_t size, bool is_promotion) {
+ // New object should fit the PLAB size
+ size_t min_size = MAX2(size, PLAB::min_size());
+
+ // Figure out size of new PLAB, looking back at heuristics. Expand aggressively.
+ size_t cur_size = ShenandoahThreadLocalData::plab_size(thread);
+ if (cur_size == 0) {
+ cur_size = PLAB::min_size();
+ }
+ size_t future_size = cur_size * 2;
+ // Limit growth of PLABs to ShenandoahMaxEvacLABRatio * the minimum size. This enables more equitable distribution of
+ // available evacuation buidget between the many threads that are coordinating in the evacuation effort.
+ if (ShenandoahMaxEvacLABRatio > 0) {
+ future_size = MIN2(future_size, PLAB::min_size() * ShenandoahMaxEvacLABRatio);
+ }
+ future_size = MIN2(future_size, PLAB::max_size());
+ future_size = MAX2(future_size, PLAB::min_size());
+
+ size_t unalignment = future_size % CardTable::card_size_in_words();
+ if (unalignment != 0) {
+ future_size = future_size - unalignment + CardTable::card_size_in_words();
+ }
+
+ // Record new heuristic value even if we take any shortcut. This captures
+ // the case when moderately-sized objects always take a shortcut. At some point,
+ // heuristics should catch up with them. Note that the requested cur_size may
+ // not be honored, but we remember that this is the preferred size.
+ ShenandoahThreadLocalData::set_plab_size(thread, future_size);
+ if (cur_size < size) {
+ // The PLAB to be allocated is still not large enough to hold the object. Fall back to shared allocation.
+ // This avoids retiring perfectly good PLABs in order to represent a single large object allocation.
+ return nullptr;
+ }
+
+ // Retire current PLAB, and allocate a new one.
+ PLAB* plab = ShenandoahThreadLocalData::plab(thread);
+ if (plab->words_remaining() < PLAB::min_size()) {
+ // Retire current PLAB, and allocate a new one.
+ // CAUTION: retire_plab may register the remnant filler object with the remembered set scanner without a lock. This
+ // is safe iff it is assured that each PLAB is a whole-number multiple of card-mark memory size and each PLAB is
+ // aligned with the start of a card's memory range.
+ retire_plab(plab, thread);
+
+ size_t actual_size = 0;
+ // allocate_new_plab resets plab_evacuated and plab_promoted and disables promotions if old-gen available is
+ // less than the remaining evacuation need. It also adjusts plab_preallocated and expend_promoted if appropriate.
+ HeapWord* plab_buf = allocate_new_plab(min_size, cur_size, &actual_size);
+ if (plab_buf == nullptr) {
+ if (min_size == PLAB::min_size()) {
+ // Disable plab promotions for this thread because we cannot even allocate a plab of minimal size. This allows us
+ // to fail faster on subsequent promotion attempts.
+ ShenandoahThreadLocalData::disable_plab_promotions(thread);
+ }
+ return NULL;
+ } else {
+ ShenandoahThreadLocalData::enable_plab_retries(thread);
+ }
+ assert (size <= actual_size, "allocation should fit");
+ if (ZeroTLAB) {
+ // ..and clear it.
+ Copy::zero_to_words(plab_buf, actual_size);
+ } else {
+ // ...and zap just allocated object.
+ #ifdef ASSERT
+ // Skip mangling the space corresponding to the object header to
+ // ensure that the returned space is not considered parsable by
+ // any concurrent GC thread.
+ size_t hdr_size = oopDesc::header_size();
+ Copy::fill_to_words(plab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
+ #endif // ASSERT
+ }
+ plab->set_buf(plab_buf, actual_size);
+ if (is_promotion && !ShenandoahThreadLocalData::allow_plab_promotions(thread)) {
+ return nullptr;
+ }
+ return plab->allocate(size);
+ } else {
+ // If there's still at least min_size() words available within the current plab, don't retire it. Let's gnaw
+ // away on this plab as long as we can. Meanwhile, return nullptr to force this particular allocation request
+ // to be satisfied with a shared allocation. By packing more promotions into the previously allocated PLAB, we
+ // reduce the likelihood of evacuation failures, and we we reduce the need for downsizing our PLABs.
+ return nullptr;
+ }
+ }
+
+ // TODO: It is probably most efficient to register all objects (both promotions and evacuations) that were allocated within
+ // this plab at the time we retire the plab. A tight registration loop will run within both code and data caches. This change
+ // would allow smaller and faster in-line implementation of alloc_from_plab(). Since plabs are aligned on card-table boundaries,
+ // this object registration loop can be performed without acquiring a lock.
+ void ShenandoahHeap::retire_plab(PLAB* plab, Thread* thread) {
+ // We don't enforce limits on plab_evacuated. We let it consume all available old-gen memory in order to reduce
+ // probability of an evacuation failure. We do enforce limits on promotion, to make sure that excessive promotion
+ // does not result in an old-gen evacuation failure. Note that a failed promotion is relatively harmless. Any
+ // object that fails to promote in the current cycle will be eligible for promotion in a subsequent cycle.
+
+ // When the plab was instantiated, its entirety was treated as if the entire buffer was going to be dedicated to
+ // promotions. Now that we are retiring the buffer, we adjust for the reality that the plab is not entirely promotions.
+ // 1. Some of the plab may have been dedicated to evacuations.
+ // 2. Some of the plab may have been abandoned due to waste (at the end of the plab).
+ size_t not_promoted =
+ ShenandoahThreadLocalData::get_plab_preallocated_promoted(thread) - ShenandoahThreadLocalData::get_plab_promoted(thread);
+ ShenandoahThreadLocalData::reset_plab_promoted(thread);
+ ShenandoahThreadLocalData::reset_plab_evacuated(thread);
+ ShenandoahThreadLocalData::set_plab_preallocated_promoted(thread, 0);
+ if (not_promoted > 0) {
+ unexpend_promoted(not_promoted);
+ }
+ size_t waste = plab->waste();
+ HeapWord* top = plab->top();
+ plab->retire();
+ if (top != nullptr && plab->waste() > waste && is_in_old(top)) {
+ // If retiring the plab created a filler object, then we
+ // need to register it with our card scanner so it can
+ // safely walk the region backing the plab.
+ log_debug(gc)("retire_plab() is registering remnant of size " SIZE_FORMAT " at " PTR_FORMAT,
+ plab->waste() - waste, p2i(top));
+ card_scan()->register_object_without_lock(top);
+ }
+ }
+
+ void ShenandoahHeap::retire_plab(PLAB* plab) {
+ Thread* thread = Thread::current();
+ retire_plab(plab, thread);
+ }
+
+ void ShenandoahHeap::cancel_old_gc() {
+ shenandoah_assert_safepoint();
+ assert(_old_generation != nullptr, "Should only have mixed collections in generation mode.");
+ log_info(gc)("Terminating old gc cycle.");
+
+ // Stop marking
+ old_generation()->cancel_marking();
+ // Stop coalescing undead objects
+ set_prepare_for_old_mark_in_progress(false);
+ // Stop tracking old regions
+ old_heuristics()->abandon_collection_candidates();
+ // Remove old generation access to young generation mark queues
+ young_generation()->set_old_gen_task_queues(nullptr);
+ // Transition to IDLE now.
+ _old_generation->transition_to(ShenandoahOldGeneration::IDLE);
+ }
+
+ bool ShenandoahHeap::is_old_gc_active() {
+ return _old_generation->state() != ShenandoahOldGeneration::IDLE;
+ }
+
+ // xfer_limit is the maximum we're able to transfer from young to old
+ void ShenandoahHeap::adjust_generation_sizes_for_next_cycle(
+ size_t xfer_limit, size_t young_cset_regions, size_t old_cset_regions) {
+
+ // Make sure old-generation is large enough, but no larger, than is necessary to hold mixed evacuations
+ // and promotions if we anticipate either.
+ size_t region_size_bytes = ShenandoahHeapRegion::region_size_bytes();
+ size_t promo_load = get_promotion_potential();
+ // The free set will reserve this amount of memory to hold young evacuations
+ size_t young_reserve = (young_generation()->max_capacity() * ShenandoahEvacReserve) / 100;
+ size_t old_reserve = 0;
+ size_t mixed_candidates = old_heuristics()->unprocessed_old_collection_candidates();
+ bool doing_mixed = (mixed_candidates > 0);
+ bool doing_promotions = promo_load > 0;
+
+ // round down
+ size_t max_old_region_xfer = xfer_limit / region_size_bytes;
+
+ // We can limit the reserve to the size of anticipated promotions
+ size_t max_old_reserve = young_reserve * ShenandoahOldEvacRatioPercent / (100 - ShenandoahOldEvacRatioPercent);
+ // Here's the algebra:
+ // TotalEvacuation = OldEvacuation + YoungEvacuation
+ // OldEvacuation = TotalEvacuation*(ShenandoahOldEvacRatioPercent/100)
+ // OldEvacuation = YoungEvacuation * (ShenandoahOldEvacRatioPercent/100)/(1 - ShenandoahOldEvacRatioPercent/100)
+ // OldEvacuation = YoungEvacuation * ShenandoahOldEvacRatioPercent/(100 - ShenandoahOldEvacRatioPercent)
+
+ size_t reserve_for_mixed, reserve_for_promo;
+ if (doing_mixed) {
+ assert(old_generation()->available() >= old_generation()->free_unaffiliated_regions() * region_size_bytes,
+ "Unaffiliated available must be less than total available");
+
+ // We want this much memory to be unfragmented in order to reliably evacuate old. This is conservative because we
+ // may not evacuate the entirety of unprocessed candidates in a single mixed evacuation.
+ size_t max_evac_need = (size_t)
+ (old_heuristics()->unprocessed_old_collection_candidates_live_memory() * ShenandoahOldEvacWaste);
+ size_t old_fragmented_available =
+ old_generation()->available() - old_generation()->free_unaffiliated_regions() * region_size_bytes;
+ reserve_for_mixed = max_evac_need + old_fragmented_available;
+ if (reserve_for_mixed > max_old_reserve) {
+ reserve_for_mixed = max_old_reserve;
+ }
+ } else {
+ reserve_for_mixed = 0;
+ }
+
+ size_t available_for_promotions = max_old_reserve - reserve_for_mixed;
+ if (doing_promotions) {
+ // We're only promoting and we have a maximum bound on the amount to be promoted
+ reserve_for_promo = (size_t) (promo_load * ShenandoahPromoEvacWaste);
+ if (reserve_for_promo > available_for_promotions) {
+ reserve_for_promo = available_for_promotions;
+ }
+ } else {
+ reserve_for_promo = 0;
+ }
+ old_reserve = reserve_for_mixed + reserve_for_promo;
+ assert(old_reserve <= max_old_reserve, "cannot reserve more than max for old evacuations");
+ size_t old_available = old_generation()->available() + old_cset_regions * region_size_bytes;
+ size_t young_available = young_generation()->available() + young_cset_regions * region_size_bytes;
+ size_t old_region_deficit = 0;
+ size_t old_region_surplus = 0;
+ if (old_available >= old_reserve) {
+ size_t old_excess = old_available - old_reserve;
+ size_t excess_regions = old_excess / region_size_bytes;
+ size_t unaffiliated_old_regions = old_generation()->free_unaffiliated_regions() + old_cset_regions;
+ size_t unaffiliated_old = unaffiliated_old_regions * region_size_bytes;
+ if (unaffiliated_old_regions < excess_regions) {
+ // We'll give only unaffiliated old to young, which is known to be less than the excess.
+ old_region_surplus = unaffiliated_old_regions;
+ } else {
+ // unaffiliated_old_regions > excess_regions, so we only give away the excess.
+ old_region_surplus = excess_regions;
+ }
+ } else {
+ // We need to request transfer from YOUNG. Ignore that this will directly impact young_generation()->max_capacity(),
+ // indirectly impacting young_reserve and old_reserve. These computations are conservative.
+ size_t old_need = old_reserve - old_available;
+ // Round up the number of regions needed from YOUNG
+ old_region_deficit = (old_need + region_size_bytes - 1) / region_size_bytes;
+ }
+ if (old_region_deficit > max_old_region_xfer) {
+ // If we're running short on young-gen memory, limit the xfer. Old-gen collection activities will be curtailed
+ // if the budget is smaller than desired.
+ old_region_deficit = max_old_region_xfer;
+ }
+ set_old_region_surplus(old_region_surplus);
+ set_old_region_deficit(old_region_deficit);
+ }
+
+ // Called from stubs in JIT code or interpreter
HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
size_t requested_size,
size_t* actual_size) {
ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
- HeapWord* res = allocate_memory(req);
+ HeapWord* res = allocate_memory(req, false);
if (res != nullptr) {
*actual_size = req.actual_size();
} else {
*actual_size = 0;
}
HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
size_t word_size,
size_t* actual_size) {
ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
- HeapWord* res = allocate_memory(req);
+ HeapWord* res = allocate_memory(req, false);
+ if (res != nullptr) {
+ *actual_size = req.actual_size();
+ } else {
+ *actual_size = 0;
+ }
+ return res;
+ }
+
+ HeapWord* ShenandoahHeap::allocate_new_plab(size_t min_size,
+ size_t word_size,
+ size_t* actual_size) {
+ // Align requested sizes to card sized multiples
+ size_t words_in_card = CardTable::card_size_in_words();
+ size_t align_mask = ~(words_in_card - 1);
+ min_size = (min_size + words_in_card - 1) & align_mask;
+ word_size = (word_size + words_in_card - 1) & align_mask;
+ ShenandoahAllocRequest req = ShenandoahAllocRequest::for_plab(min_size, word_size);
+ // Note that allocate_memory() sets a thread-local flag to prohibit further promotions by this thread
+ // if we are at risk of infringing on the old-gen evacuation budget.
+ HeapWord* res = allocate_memory(req, false);
if (res != nullptr) {
*actual_size = req.actual_size();
} else {
*actual_size = 0;
}
return res;
}
- HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
+ // is_promotion is true iff this allocation is known for sure to hold the result of young-gen evacuation
+ // to old-gen. plab allocates are not known as such, since they may hold old-gen evacuations.
+ HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req, bool is_promotion) {
intptr_t pacer_epoch = 0;
bool in_new_region = false;
HeapWord* result = nullptr;
if (req.is_mutator_alloc()) {
pacer()->pace_for_alloc(req.size());
pacer_epoch = pacer()->epoch();
}
if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
- result = allocate_memory_under_lock(req, in_new_region);
+ result = allocate_memory_under_lock(req, in_new_region, is_promotion);
}
// Allocation failed, block until control thread reacted, then retry allocation.
//
// It might happen that one of the threads requesting allocation would unblock
// one full GC has completed).
size_t original_count = shenandoah_policy()->full_gc_count();
while (result == nullptr
&& (_progress_last_gc.is_set() || original_count == shenandoah_policy()->full_gc_count())) {
control_thread()->handle_alloc_failure(req);
- result = allocate_memory_under_lock(req, in_new_region);
+ result = allocate_memory_under_lock(req, in_new_region, is_promotion);
}
+
} else {
assert(req.is_gc_alloc(), "Can only accept GC allocs here");
- result = allocate_memory_under_lock(req, in_new_region);
+ result = allocate_memory_under_lock(req, in_new_region, is_promotion);
// Do not call handle_alloc_failure() here, because we cannot block.
// The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
}
if (in_new_region) {
control_thread()->notify_heap_changed();
+ regulator_thread()->notify_heap_changed();
}
+ if (result == nullptr) {
+ req.set_actual_size(0);
+ }
+
+ // This is called regardless of the outcome of the allocation to account
+ // for any waste created by retiring regions with this request.
+ increase_used(req);
+
if (result != nullptr) {
size_t requested = req.size();
size_t actual = req.actual_size();
assert (req.is_lab_alloc() || (requested == actual),
"Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
if (req.is_mutator_alloc()) {
- notify_mutator_alloc_words(actual, false);
-
// If we requested more than we were granted, give the rest back to pacer.
// This only matters if we are in the same pacing epoch: do not try to unpace
// over the budget for the other phase.
if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
}
- } else {
- increase_used(actual*HeapWordSize);
}
}
return result;
}
- HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
- ShenandoahHeapLocker locker(lock());
- return _free_set->allocate(req, in_new_region);
+ HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region, bool is_promotion) {
+ bool try_smaller_lab_size = false;
+ size_t smaller_lab_size;
+ {
+ // promotion_eligible pertains only to PLAB allocations, denoting that the PLAB is allowed to allocate for promotions.
+ bool promotion_eligible = false;
+ bool allow_allocation = true;
+ bool plab_alloc = false;
+ size_t requested_bytes = req.size() * HeapWordSize;
+ HeapWord* result = nullptr;
+ ShenandoahHeapLocker locker(lock());
+ Thread* thread = Thread::current();
+
+ if (mode()->is_generational()) {
+ if (req.affiliation() == YOUNG_GENERATION) {
+ if (req.is_mutator_alloc()) {
+ size_t young_words_available = young_generation()->available() / HeapWordSize;
+ if (ShenandoahElasticTLAB && req.is_lab_alloc() && (req.min_size() < young_words_available)) {
+ // Allow ourselves to try a smaller lab size even if requested_bytes <= young_available. We may need a smaller
+ // lab size because young memory has become too fragmented.
+ try_smaller_lab_size = true;
+ smaller_lab_size = (young_words_available < req.size())? young_words_available: req.size();
+ } else if (req.size() > young_words_available) {
+ // Can't allocate because even min_size() is larger than remaining young_available
+ log_info(gc, ergo)("Unable to shrink %s alloc request of minimum size: " SIZE_FORMAT
+ ", young words available: " SIZE_FORMAT, req.type_string(),
+ HeapWordSize * (req.is_lab_alloc()? req.min_size(): req.size()), young_words_available);
+ return nullptr;
+ }
+ }
+ } else { // reg.affiliation() == OLD_GENERATION
+ assert(req.type() != ShenandoahAllocRequest::_alloc_gclab, "GCLAB pertains only to young-gen memory");
+ if (req.type() == ShenandoahAllocRequest::_alloc_plab) {
+ plab_alloc = true;
+ size_t promotion_avail = get_promoted_reserve();
+ size_t promotion_expended = get_promoted_expended();
+ if (promotion_expended + requested_bytes > promotion_avail) {
+ promotion_avail = 0;
+ if (get_old_evac_reserve() == 0) {
+ // There are no old-gen evacuations in this pass. There's no value in creating a plab that cannot
+ // be used for promotions.
+ allow_allocation = false;
+ }
+ } else {
+ promotion_avail = promotion_avail - (promotion_expended + requested_bytes);
+ promotion_eligible = true;
+ }
+ } else if (is_promotion) {
+ // This is a shared alloc for promotion
+ size_t promotion_avail = get_promoted_reserve();
+ size_t promotion_expended = get_promoted_expended();
+ if (promotion_expended + requested_bytes > promotion_avail) {
+ promotion_avail = 0;
+ } else {
+ promotion_avail = promotion_avail - (promotion_expended + requested_bytes);
+ }
+ if (promotion_avail == 0) {
+ // We need to reserve the remaining memory for evacuation. Reject this allocation. The object will be
+ // evacuated to young-gen memory and promoted during a future GC pass.
+ return nullptr;
+ }
+ // Else, we'll allow the allocation to proceed. (Since we hold heap lock, the tested condition remains true.)
+ } else {
+ // This is a shared allocation for evacuation. Memory has already been reserved for this purpose.
+ }
+ }
+ } // This ends the is_generational() block
+
+ // First try the original request. If TLAB request size is greater than available, allocate() will attempt to downsize
+ // request to fit within available memory.
+ result = (allow_allocation)? _free_set->allocate(req, in_new_region): nullptr;
+ if (result != nullptr) {
+ if (req.is_old()) {
+ ShenandoahThreadLocalData::reset_plab_promoted(thread);
+ if (req.is_gc_alloc()) {
+ bool disable_plab_promotions = false;
+ if (req.type() == ShenandoahAllocRequest::_alloc_plab) {
+ if (promotion_eligible) {
+ size_t actual_size = req.actual_size() * HeapWordSize;
+ // The actual size of the allocation may be larger than the requested bytes (due to alignment on card boundaries).
+ // If this puts us over our promotion budget, we need to disable future PLAB promotions for this thread.
+ if (get_promoted_expended() + actual_size <= get_promoted_reserve()) {
+ // Assume the entirety of this PLAB will be used for promotion. This prevents promotion from overreach.
+ // When we retire this plab, we'll unexpend what we don't really use.
+ ShenandoahThreadLocalData::enable_plab_promotions(thread);
+ expend_promoted(actual_size);
+ assert(get_promoted_expended() <= get_promoted_reserve(), "Do not expend more promotion than budgeted");
+ ShenandoahThreadLocalData::set_plab_preallocated_promoted(thread, actual_size);
+ } else {
+ disable_plab_promotions = true;
+ }
+ } else {
+ disable_plab_promotions = true;
+ }
+ if (disable_plab_promotions) {
+ // Disable promotions in this thread because entirety of this PLAB must be available to hold old-gen evacuations.
+ ShenandoahThreadLocalData::disable_plab_promotions(thread);
+ ShenandoahThreadLocalData::set_plab_preallocated_promoted(thread, 0);
+ }
+ } else if (is_promotion) {
+ // Shared promotion. Assume size is requested_bytes.
+ expend_promoted(requested_bytes);
+ assert(get_promoted_expended() <= get_promoted_reserve(), "Do not expend more promotion than budgeted");
+ }
+ }
+
+ // Register the newly allocated object while we're holding the global lock since there's no synchronization
+ // built in to the implementation of register_object(). There are potential races when multiple independent
+ // threads are allocating objects, some of which might span the same card region. For example, consider
+ // a card table's memory region within which three objects are being allocated by three different threads:
+ //
+ // objects being "concurrently" allocated:
+ // [-----a------][-----b-----][--------------c------------------]
+ // [---- card table memory range --------------]
+ //
+ // Before any objects are allocated, this card's memory range holds no objects. Note that allocation of object a
+ // wants to set the starts-object, first-start, and last-start attributes of the preceding card region.
+ // allocation of object b wants to set the starts-object, first-start, and last-start attributes of this card region.
+ // allocation of object c also wants to set the starts-object, first-start, and last-start attributes of this
+ // card region.
+ //
+ // The thread allocating b and the thread allocating c can "race" in various ways, resulting in confusion, such as
+ // last-start representing object b while first-start represents object c. This is why we need to require all
+ // register_object() invocations to be "mutually exclusive" with respect to each card's memory range.
+ ShenandoahHeap::heap()->card_scan()->register_object(result);
+ }
+ } else {
+ // The allocation failed. If this was a plab allocation, We've already retired it and no longer have a plab.
+ if (req.is_old() && req.is_gc_alloc() && (req.type() == ShenandoahAllocRequest::_alloc_plab)) {
+ // We don't need to disable PLAB promotions because there is no PLAB. We leave promotions enabled because
+ // this allows the surrounding infrastructure to retry alloc_plab_slow() with a smaller PLAB size.
+ ShenandoahThreadLocalData::set_plab_preallocated_promoted(thread, 0);
+ }
+ }
+ if ((result != nullptr) || !try_smaller_lab_size) {
+ return result;
+ }
+ // else, fall through to try_smaller_lab_size
+ } // This closes the block that holds the heap lock, releasing the lock.
+
+ // We failed to allocate the originally requested lab size. Let's see if we can allocate a smaller lab size.
+ if (req.size() == smaller_lab_size) {
+ // If we were already trying to allocate min size, no value in attempting to repeat the same. End the recursion.
+ return nullptr;
+ }
+
+ // We arrive here if the tlab allocation request can be resized to fit within young_available
+ assert((req.affiliation() == YOUNG_GENERATION) && req.is_lab_alloc() && req.is_mutator_alloc() &&
+ (smaller_lab_size < req.size()), "Only shrink allocation request size for TLAB allocations");
+
+ // By convention, ShenandoahAllocationRequest is primarily read-only. The only mutable instance data is represented by
+ // actual_size(), which is overwritten with the size of the allocaion when the allocation request is satisfied. We use a
+ // recursive call here rather than introducing new methods to mutate the existing ShenandoahAllocationRequest argument.
+ // Mutation of the existing object might result in astonishing results if calling contexts assume the content of immutable
+ // fields remain constant. The original TLAB allocation request was for memory that exceeded the current capacity. We'll
+ // attempt to allocate a smaller TLAB. If this is successful, we'll update actual_size() of our incoming
+ // ShenandoahAllocRequest. If the recursive request fails, we'll simply return nullptr.
+
+ // Note that we've relinquished the HeapLock and some other thread may perform additional allocation before our recursive
+ // call reacquires the lock. If that happens, we will need another recursive call to further reduce the size of our request
+ // for each time another thread allocates young memory during the brief intervals that the heap lock is available to
+ // interfering threads. We expect this interference to be rare. The recursion bottoms out when young_available is
+ // smaller than req.min_size(). The inner-nested call to allocate_memory_under_lock() uses the same min_size() value
+ // as this call, but it uses a preferred size() that is smaller than our preferred size, and is no larger than what we most
+ // recently saw as the memory currently available within the young generation.
+
+ // TODO: At the expense of code clarity, we could rewrite this recursive solution to use iteration. We need at most one
+ // extra instance of the ShenandoahAllocRequest, which we can re-initialize multiple times inside a loop, with one iteration
+ // of the loop required for each time the existing solution would recurse. An iterative solution would be more efficient
+ // in CPU time and stack memory utilization. The expectation is that it is very rare that we would recurse more than once
+ // so making this change is not currently seen as a high priority.
+
+ ShenandoahAllocRequest smaller_req = ShenandoahAllocRequest::for_tlab(req.min_size(), smaller_lab_size);
+
+ // Note that shrinking the preferred size gets us past the gatekeeper that checks whether there's available memory to
+ // satisfy the allocation request. The reality is the actual TLAB size is likely to be even smaller, because it will
+ // depend on how much memory is available within mutator regions that are not yet fully used.
+ HeapWord* result = allocate_memory_under_lock(smaller_req, in_new_region, is_promotion);
+ if (result != nullptr) {
+ req.set_actual_size(smaller_req.actual_size());
+ }
+ return result;
}
HeapWord* ShenandoahHeap::mem_allocate(size_t size,
bool* gc_overhead_limit_was_exceeded) {
ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
- return allocate_memory(req);
+ return allocate_memory(req, false);
}
MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
size_t size,
Metaspace::MetadataType mdtype) {
MetaWord* result;
// Inform metaspace OOM to GC heuristics if class unloading is possible.
- if (heuristics()->can_unload_classes()) {
- ShenandoahHeuristics* h = heuristics();
+ ShenandoahHeuristics* h = global_generation()->heuristics();
+ if (h->can_unload_classes()) {
h->record_metaspace_oom();
}
// Expand and retry allocation
result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
void do_work() {
ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
ShenandoahHeapRegion* r;
while ((r =_cs->claim_next()) != nullptr) {
assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
+
_sh->marked_object_iterate(r, &cl);
if (ShenandoahPacing) {
_sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
}
+ if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
+ break;
+ }
+ }
+ }
+ };
+
+ // Unlike ShenandoahEvacuationTask, this iterates over all regions rather than just the collection set.
+ // This is needed in order to promote humongous start regions if age() >= tenure threshold.
+ class ShenandoahGenerationalEvacuationTask : public WorkerTask {
+ private:
+ ShenandoahHeap* const _sh;
+ ShenandoahRegionIterator *_regions;
+ bool _concurrent;
+ uint _tenuring_threshold;
+
+ public:
+ ShenandoahGenerationalEvacuationTask(ShenandoahHeap* sh,
+ ShenandoahRegionIterator* iterator,
+ bool concurrent) :
+ WorkerTask("Shenandoah Evacuation"),
+ _sh(sh),
+ _regions(iterator),
+ _concurrent(concurrent),
+ _tenuring_threshold(0)
+ {
+ if (_sh->mode()->is_generational()) {
+ _tenuring_threshold = _sh->age_census()->tenuring_threshold();
+ }
+ }
+
+ void work(uint worker_id) {
+ if (_concurrent) {
+ ShenandoahConcurrentWorkerSession worker_session(worker_id);
+ ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
+ ShenandoahEvacOOMScope oom_evac_scope;
+ do_work();
+ } else {
+ ShenandoahParallelWorkerSession worker_session(worker_id);
+ ShenandoahEvacOOMScope oom_evac_scope;
+ do_work();
+ }
+ }
+
+ private:
+ void do_work() {
+ ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
+ ShenandoahHeapRegion* r;
+ ShenandoahMarkingContext* const ctx = ShenandoahHeap::heap()->marking_context();
+ size_t region_size_bytes = ShenandoahHeapRegion::region_size_bytes();
+ size_t old_garbage_threshold = (region_size_bytes * ShenandoahOldGarbageThreshold) / 100;
+ while ((r = _regions->next()) != nullptr) {
+ log_debug(gc)("GenerationalEvacuationTask do_work(), looking at %s region " SIZE_FORMAT ", (age: %d) [%s, %s, %s]",
+ r->is_old()? "old": r->is_young()? "young": "free", r->index(), r->age(),
+ r->is_active()? "active": "inactive",
+ r->is_humongous()? (r->is_humongous_start()? "humongous_start": "humongous_continuation"): "regular",
+ r->is_cset()? "cset": "not-cset");
+
+ if (r->is_cset()) {
+ assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
+ _sh->marked_object_iterate(r, &cl);
+ if (ShenandoahPacing) {
+ _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
+ }
+ } else if (r->is_young() && r->is_active() && (r->age() >= _tenuring_threshold)) {
+ HeapWord* tams = ctx->top_at_mark_start(r);
+ if (r->is_humongous_start()) {
+ // We promote humongous_start regions along with their affiliated continuations during evacuation rather than
+ // doing this work during a safepoint. We cannot put humongous regions into the collection set because that
+ // triggers the load-reference barrier (LRB) to copy on reference fetch.
+ r->promote_humongous();
+ } else if (r->is_regular() && (r->get_top_before_promote() != nullptr)) {
+ assert(r->garbage_before_padded_for_promote() < old_garbage_threshold,
+ "Region " SIZE_FORMAT " has too much garbage for promotion", r->index());
+ assert(r->get_top_before_promote() == tams,
+ "Region " SIZE_FORMAT " has been used for allocations before promotion", r->index());
+ // Likewise, we cannot put promote-in-place regions into the collection set because that would also trigger
+ // the LRB to copy on reference fetch.
+ r->promote_in_place();
+ }
+ // Aged humongous continuation regions are handled with their start region. If an aged regular region has
+ // more garbage than ShenandoahOldGarbageTrheshold, we'll promote by evacuation. If there is room for evacuation
+ // in this cycle, the region will be in the collection set. If there is not room, the region will be promoted
+ // by evacuation in some future GC cycle.
+
+ // If an aged regular region has received allocations during the current cycle, we do not promote because the
+ // newly allocated objects do not have appropriate age; this region's age will be reset to zero at end of cycle.
+ }
+ // else, region is free, or OLD, or not in collection set, or humongous_continuation,
+ // or is young humongous_start that is too young to be promoted
if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
break;
}
}
}
};
void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
- ShenandoahEvacuationTask task(this, _collection_set, concurrent);
- workers()->run_task(&task);
+ if (ShenandoahHeap::heap()->mode()->is_generational()) {
+ ShenandoahRegionIterator regions;
+ ShenandoahGenerationalEvacuationTask task(this, ®ions, concurrent);
+ workers()->run_task(&task);
+ } else {
+ ShenandoahEvacuationTask task(this, _collection_set, concurrent);
+ workers()->run_task(&task);
+ }
}
void ShenandoahHeap::trash_cset_regions() {
ShenandoahHeapLocker locker(lock());
for (size_t i = 0; i < num_regions(); i++) {
get_region(i)->print_on(st);
}
}
- void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
+ size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
assert(start->is_humongous_start(), "reclaim regions starting with the first one");
oop humongous_obj = cast_to_oop(start->bottom());
size_t size = humongous_obj->size();
size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
assert(region->is_humongous(), "expect correct humongous start or continuation");
assert(!region->is_cset(), "Humongous region should not be in collection set");
region->make_trash_immediate();
}
+ return required_regions;
}
class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
public:
ShenandoahCheckCleanGCLABClosure() {}
void do_thread(Thread* thread) {
PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
+
+ PLAB* plab = ShenandoahThreadLocalData::plab(thread);
+ assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
+ assert(plab->words_remaining() == 0, "PLAB should not need retirement");
}
};
class ShenandoahRetireGCLABClosure : public ThreadClosure {
private:
assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
gclab->retire();
if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
ShenandoahThreadLocalData::set_gclab_size(thread, 0);
}
+
+ PLAB* plab = ShenandoahThreadLocalData::plab(thread);
+ assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
+
+ // There are two reasons to retire all plabs between old-gen evacuation passes.
+ // 1. We need to make the plab memory parseable by remembered-set scanning.
+ // 2. We need to establish a trustworthy UpdateWaterMark value within each old-gen heap region
+ ShenandoahHeap::heap()->retire_plab(plab, thread);
+ if (_resize && ShenandoahThreadLocalData::plab_size(thread) > 0) {
+ ShenandoahThreadLocalData::set_plab_size(thread, 0);
+ }
}
};
void ShenandoahHeap::labs_make_parsable() {
assert(UseTLAB, "Only call with UseTLAB");
if (safepoint_workers() != nullptr) {
safepoint_workers()->threads_do(&cl);
}
}
+ class ShenandoahTagGCLABClosure : public ThreadClosure {
+ public:
+ void do_thread(Thread* thread) {
+ PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
+ assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
+ if (gclab->words_remaining() > 0) {
+ ShenandoahHeapRegion* r = ShenandoahHeap::heap()->heap_region_containing(gclab->allocate(0));
+ r->set_young_lab_flag();
+ }
+ }
+ };
+
+ void ShenandoahHeap::set_young_lab_region_flags() {
+ if (!UseTLAB) {
+ return;
+ }
+ for (size_t i = 0; i < _num_regions; i++) {
+ _regions[i]->clear_young_lab_flags();
+ }
+ ShenandoahTagGCLABClosure cl;
+ workers()->threads_do(&cl);
+ for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
+ cl.do_thread(t);
+ ThreadLocalAllocBuffer& tlab = t->tlab();
+ if (tlab.end() != nullptr) {
+ ShenandoahHeapRegion* r = heap_region_containing(tlab.start());
+ r->set_young_lab_flag();
+ }
+ }
+ }
+
// Returns size in bytes
size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
if (ShenandoahElasticTLAB) {
- // With Elastic TLABs, return the max allowed size, and let the allocation path
- // figure out the safe size for current allocation.
- return ShenandoahHeapRegion::max_tlab_size_bytes();
+ if (mode()->is_generational()) {
+ return MIN2(ShenandoahHeapRegion::max_tlab_size_bytes(), young_generation()->available());
+ } else {
+ // With Elastic TLABs, return the max allowed size, and let the allocation path
+ // figure out the safe size for current allocation.
+ return ShenandoahHeapRegion::max_tlab_size_bytes();
+ }
} else {
return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
}
}
labs_make_parsable();
}
}
void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
+ if (_shenandoah_policy->is_at_shutdown()) {
+ return;
+ }
+
tcl->do_thread(_control_thread);
+ tcl->do_thread(_regulator_thread);
workers()->threads_do(tcl);
if (_safepoint_workers != nullptr) {
_safepoint_workers->threads_do(tcl);
}
}
ls.cr();
ls.cr();
shenandoah_policy()->print_gc_stats(&ls);
+ ls.cr();
+
+ evac_tracker()->print_global_on(&ls);
+
ls.cr();
ls.cr();
}
}
+ void ShenandoahHeap::on_cycle_start(GCCause::Cause cause, ShenandoahGeneration* generation) {
+ set_gc_cause(cause);
+ set_gc_generation(generation);
+
+ shenandoah_policy()->record_cycle_start();
+ generation->heuristics()->record_cycle_start();
+ }
+
+ void ShenandoahHeap::on_cycle_end(ShenandoahGeneration* generation) {
+ generation->heuristics()->record_cycle_end();
+ if (mode()->is_generational() && (generation->is_global() || upgraded_to_full())) {
+ // If we just completed a GLOBAL GC, claim credit for completion of young-gen and old-gen GC as well
+ young_generation()->heuristics()->record_cycle_end();
+ old_generation()->heuristics()->record_cycle_end();
+ }
+ set_gc_cause(GCCause::_no_gc);
+ }
+
void ShenandoahHeap::verify(VerifyOption vo) {
if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
if (ShenandoahVerify) {
verifier()->verify_generic(vo);
} else {
} else {
heap_region_iterate(blk);
}
}
- class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
- private:
- ShenandoahMarkingContext* const _ctx;
- public:
- ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
-
- void heap_region_do(ShenandoahHeapRegion* r) {
- assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
- if (r->is_active()) {
- // Check if region needs updating its TAMS. We have updated it already during concurrent
- // reset, so it is very likely we don't need to do another write here.
- if (_ctx->top_at_mark_start(r) != r->top()) {
- _ctx->capture_top_at_mark_start(r);
- }
- } else {
- assert(_ctx->top_at_mark_start(r) == r->top(),
- "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
- }
- }
-
- bool is_thread_safe() { return true; }
- };
-
class ShenandoahRendezvousClosure : public HandshakeClosure {
public:
inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
inline void do_thread(Thread* thread) {}
};
void ShenandoahHeap::recycle_trash() {
free_set()->recycle_trash();
}
- class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
- private:
- ShenandoahMarkingContext* const _ctx;
- public:
- ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
-
- void heap_region_do(ShenandoahHeapRegion* r) {
- if (r->is_active()) {
- // Reset live data and set TAMS optimistically. We would recheck these under the pause
- // anyway to capture any updates that happened since now.
- r->clear_live_data();
- _ctx->capture_top_at_mark_start(r);
- }
- }
-
- bool is_thread_safe() { return true; }
- };
-
- void ShenandoahHeap::prepare_gc() {
- reset_mark_bitmap();
-
- ShenandoahResetUpdateRegionStateClosure cl;
- parallel_heap_region_iterate(&cl);
- }
-
- class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
- private:
- ShenandoahMarkingContext* const _ctx;
- ShenandoahHeapLock* const _lock;
-
- public:
- ShenandoahFinalMarkUpdateRegionStateClosure() :
- _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
-
- void heap_region_do(ShenandoahHeapRegion* r) {
- if (r->is_active()) {
- // All allocations past TAMS are implicitly live, adjust the region data.
- // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
- HeapWord *tams = _ctx->top_at_mark_start(r);
- HeapWord *top = r->top();
- if (top > tams) {
- r->increase_live_data_alloc_words(pointer_delta(top, tams));
- }
-
- // We are about to select the collection set, make sure it knows about
- // current pinning status. Also, this allows trashing more regions that
- // now have their pinning status dropped.
- if (r->is_pinned()) {
- if (r->pin_count() == 0) {
- ShenandoahHeapLocker locker(_lock);
- r->make_unpinned();
- }
- } else {
- if (r->pin_count() > 0) {
- ShenandoahHeapLocker locker(_lock);
- r->make_pinned();
- }
- }
-
- // Remember limit for updating refs. It's guaranteed that we get no
- // from-space-refs written from here on.
- r->set_update_watermark_at_safepoint(r->top());
- } else {
- assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
- assert(_ctx->top_at_mark_start(r) == r->top(),
- "Region " SIZE_FORMAT " should have correct TAMS", r->index());
- }
- }
-
- bool is_thread_safe() { return true; }
- };
-
- void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
- assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
- {
- ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
- ShenandoahPhaseTimings::degen_gc_final_update_region_states);
- ShenandoahFinalMarkUpdateRegionStateClosure cl;
- parallel_heap_region_iterate(&cl);
-
- assert_pinned_region_status();
- }
-
- {
- ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
- ShenandoahPhaseTimings::degen_gc_choose_cset);
- ShenandoahHeapLocker locker(lock());
- _collection_set->clear();
- heuristics()->choose_collection_set(_collection_set);
- }
-
- {
- ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
- ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
- ShenandoahHeapLocker locker(lock());
- _free_set->rebuild();
- }
- }
-
void ShenandoahHeap::do_class_unloading() {
_unloader.unload();
}
void ShenandoahHeap::stw_weak_refs(bool full_gc) {
// Weak refs processing
ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
: ShenandoahPhaseTimings::degen_gc_weakrefs;
ShenandoahTimingsTracker t(phase);
ShenandoahGCWorkerPhase worker_phase(phase);
- ref_processor()->process_references(phase, workers(), false /* concurrent */);
+ active_generation()->ref_processor()->process_references(phase, workers(), false /* concurrent */);
}
void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
_gc_state.set_cond(mask, value);
set_gc_state_all_threads(_gc_state.raw_value());
}
- void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
- assert(!has_forwarded_objects(), "Not expected before/after mark phase");
- set_gc_state_mask(MARKING, in_progress);
- ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
+ void ShenandoahHeap::set_evacuation_reserve_quantities(bool is_valid) {
+ _has_evacuation_reserve_quantities = is_valid;
+ }
+
+ void ShenandoahHeap::set_concurrent_young_mark_in_progress(bool in_progress) {
+ uint mask;
+ assert(!has_forwarded_objects(), "Young marking is not concurrent with evacuation");
+ if (!in_progress && is_concurrent_old_mark_in_progress()) {
+ assert(mode()->is_generational(), "Only generational GC has old marking");
+ assert(_gc_state.is_set(MARKING), "concurrent_old_marking_in_progress implies MARKING");
+ // If old-marking is in progress when we turn off YOUNG_MARKING, leave MARKING (and OLD_MARKING) on
+ mask = YOUNG_MARKING;
+ } else {
+ mask = MARKING | YOUNG_MARKING;
+ }
+ set_gc_state_mask(mask, in_progress);
+ manage_satb_barrier(in_progress);
+ }
+
+ void ShenandoahHeap::set_concurrent_old_mark_in_progress(bool in_progress) {
+ #ifdef ASSERT
+ // has_forwarded_objects() iff UPDATEREFS or EVACUATION
+ bool has_forwarded = has_forwarded_objects()? 1: 0;
+ bool updating_or_evacuating = _gc_state.is_set(UPDATEREFS | EVACUATION)? 1: 0;
+ assert (has_forwarded == updating_or_evacuating, "Has forwarded objects iff updating or evacuating");
+ #endif
+ if (!in_progress && is_concurrent_young_mark_in_progress()) {
+ // If young-marking is in progress when we turn off OLD_MARKING, leave MARKING (and YOUNG_MARKING) on
+ assert(_gc_state.is_set(MARKING), "concurrent_young_marking_in_progress implies MARKING");
+ set_gc_state_mask(OLD_MARKING, in_progress);
+ } else {
+ set_gc_state_mask(MARKING | OLD_MARKING, in_progress);
+ }
+ manage_satb_barrier(in_progress);
+ }
+
+ void ShenandoahHeap::set_prepare_for_old_mark_in_progress(bool in_progress) {
+ // Unlike other set-gc-state functions, this may happen outside safepoint.
+ // Is only set and queried by control thread, so no coherence issues.
+ _prepare_for_old_mark = in_progress;
+ }
+
+ void ShenandoahHeap::set_aging_cycle(bool in_progress) {
+ _is_aging_cycle.set_cond(in_progress);
+ }
+
+ void ShenandoahHeap::manage_satb_barrier(bool active) {
+ if (is_concurrent_mark_in_progress()) {
+ // Ignore request to deactivate barrier while concurrent mark is in progress.
+ // Do not attempt to re-activate the barrier if it is already active.
+ if (active && !ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
+ ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
+ }
+ } else {
+ // No concurrent marking is in progress so honor request to deactivate,
+ // but only if the barrier is already active.
+ if (!active && ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
+ ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
+ }
+ }
}
void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
set_gc_state_mask(EVACUATION, in_progress);
bool ShenandoahHeap::try_cancel_gc() {
jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
return prev == CANCELLABLE;
}
+ void ShenandoahHeap::cancel_concurrent_mark() {
+ _young_generation->cancel_marking();
+ _old_generation->cancel_marking();
+ _global_generation->cancel_marking();
+
+ ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking();
+ }
+
void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
if (try_cancel_gc()) {
FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
log_info(gc)("%s", msg.buffer());
Events::log(Thread::current(), "%s", msg.buffer());
+ _cancel_requested_time = os::elapsedTime();
+ if (cause == GCCause::_shenandoah_upgrade_to_full_gc) {
+ _upgraded_to_full = true;
+ }
}
}
uint ShenandoahHeap::max_workers() {
return _max_workers;
}
void ShenandoahHeap::stop() {
// The shutdown sequence should be able to terminate when GC is running.
- // Step 0. Notify policy to disable event recording.
+ // Step 1. Notify policy to disable event recording and prevent visiting gc threads during shutdown
_shenandoah_policy->record_shutdown();
- // Step 1. Notify control thread that we are in shutdown.
+ // Step 2. Stop requesting collections.
+ regulator_thread()->stop();
+
+ // Step 3. Notify control thread that we are in shutdown.
// Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
// Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
control_thread()->prepare_for_graceful_shutdown();
- // Step 2. Notify GC workers that we are cancelling GC.
+ // Step 4. Notify GC workers that we are cancelling GC.
cancel_gc(GCCause::_shenandoah_stop_vm);
- // Step 3. Wait until GC worker exits normally.
+ // Step 5. Wait until GC worker exits normally.
control_thread()->stop();
}
void ShenandoahHeap::stw_unload_classes(bool full_gc) {
if (!unload_classes()) return;
ShenandoahHeap* heap = ShenandoahHeap::heap();
assert(heap->collection_set() != nullptr, "Sanity");
return (address) heap->collection_set()->biased_map_address();
}
- address ShenandoahHeap::cancelled_gc_addr() {
- return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
- }
-
address ShenandoahHeap::gc_state_addr() {
return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
}
- size_t ShenandoahHeap::bytes_allocated_since_gc_start() const {
- return Atomic::load(&_bytes_allocated_since_gc_start);
- }
-
void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
- Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
+ if (mode()->is_generational()) {
+ young_generation()->reset_bytes_allocated_since_gc_start();
+ old_generation()->reset_bytes_allocated_since_gc_start();
+ }
+
+ global_generation()->reset_bytes_allocated_since_gc_start();
}
void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
_degenerated_gc_in_progress.set_cond(in_progress);
}
#ifdef ASSERT
void ShenandoahHeap::assert_pinned_region_status() {
for (size_t i = 0; i < num_regions(); i++) {
ShenandoahHeapRegion* r = get_region(i);
- assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
- "Region " SIZE_FORMAT " pinning status is inconsistent", i);
+ if (active_generation()->contains(r)) {
+ assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
+ "Region " SIZE_FORMAT " pinning status is inconsistent", i);
+ }
}
}
#endif
ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
template<bool CONCURRENT>
class ShenandoahUpdateHeapRefsTask : public WorkerTask {
private:
ShenandoahHeap* _heap;
ShenandoahRegionIterator* _regions;
+ ShenandoahRegionChunkIterator* _work_chunks;
+
public:
- ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
+ explicit ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions,
+ ShenandoahRegionChunkIterator* work_chunks) :
WorkerTask("Shenandoah Update References"),
_heap(ShenandoahHeap::heap()),
- _regions(regions) {
+ _regions(regions),
+ _work_chunks(work_chunks)
+ {
}
void work(uint worker_id) {
if (CONCURRENT) {
ShenandoahConcurrentWorkerSession worker_session(worker_id);
ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
- do_work<ShenandoahConcUpdateRefsClosure>();
+ do_work<ShenandoahConcUpdateRefsClosure>(worker_id);
} else {
ShenandoahParallelWorkerSession worker_session(worker_id);
- do_work<ShenandoahSTWUpdateRefsClosure>();
+ do_work<ShenandoahSTWUpdateRefsClosure>(worker_id);
}
}
private:
template<class T>
- void do_work() {
+ void do_work(uint worker_id) {
T cl;
+ if (CONCURRENT && (worker_id == 0)) {
+ // We ask the first worker to replenish the Mutator free set by moving regions previously reserved to hold the
+ // results of evacuation. These reserves are no longer necessary because evacuation has completed.
+ size_t cset_regions = _heap->collection_set()->count();
+ // We cannot transfer any more regions than will be reclaimed when the existing collection set is recycled, because
+ // we need the reclaimed collection set regions to replenish the collector reserves
+ _heap->free_set()->move_collector_sets_to_mutator(cset_regions);
+ }
+ // If !CONCURRENT, there's no value in expanding Mutator free set
+
ShenandoahHeapRegion* r = _regions->next();
- ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
+ // We update references for global, old, and young collections.
+ assert(_heap->active_generation()->is_mark_complete(), "Expected complete marking");
+ ShenandoahMarkingContext* const ctx = _heap->marking_context();
+ bool is_mixed = _heap->collection_set()->has_old_regions();
while (r != nullptr) {
HeapWord* update_watermark = r->get_update_watermark();
assert (update_watermark >= r->bottom(), "sanity");
+
+ log_debug(gc)("ShenandoahUpdateHeapRefsTask::do_work(%u) looking at region " SIZE_FORMAT, worker_id, r->index());
+ bool region_progress = false;
if (r->is_active() && !r->is_cset()) {
- _heap->marked_object_oop_iterate(r, &cl, update_watermark);
+ if (!_heap->mode()->is_generational() || r->is_young()) {
+ _heap->marked_object_oop_iterate(r, &cl, update_watermark);
+ region_progress = true;
+ } else if (r->is_old()) {
+ if (_heap->active_generation()->is_global()) {
+ // Note that GLOBAL collection is not as effectively balanced as young and mixed cycles. This is because
+ // concurrent GC threads are parceled out entire heap regions of work at a time and there
+ // is no "catchup phase" consisting of remembered set scanning, during which parcels of work are smaller
+ // and more easily distributed more fairly across threads.
+
+ // TODO: Consider an improvement to load balance GLOBAL GC.
+ _heap->marked_object_oop_iterate(r, &cl, update_watermark);
+ region_progress = true;
+ }
+ // Otherwise, this is an old region in a young or mixed cycle. Process it during a second phase, below.
+ // Don't bother to report pacing progress in this case.
+ } else {
+ // Because updating of references runs concurrently, it is possible that a FREE inactive region transitions
+ // to a non-free active region while this loop is executing. Whenever this happens, the changing of a region's
+ // active status may propagate at a different speed than the changing of the region's affiliation.
+
+ // When we reach this control point, it is because a race has allowed a region's is_active() status to be seen
+ // by this thread before the region's affiliation() is seen by this thread.
+
+ // It's ok for this race to occur because the newly transformed region does not have any references to be
+ // updated.
+
+ assert(r->get_update_watermark() == r->bottom(),
+ "%s Region " SIZE_FORMAT " is_active but not recognized as YOUNG or OLD so must be newly transitioned from FREE",
+ r->affiliation_name(), r->index());
+ }
}
- if (ShenandoahPacing) {
+ if (region_progress && ShenandoahPacing) {
_heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
}
if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
return;
}
r = _regions->next();
}
+
+ if (_heap->mode()->is_generational() && !_heap->active_generation()->is_global()) {
+ // Since this is generational and not GLOBAL, we have to process the remembered set. There's no remembered
+ // set processing if not in generational mode or if GLOBAL mode.
+
+ // After this thread has exhausted its traditional update-refs work, it continues with updating refs within remembered set.
+ // The remembered set workload is better balanced between threads, so threads that are "behind" can catch up with other
+ // threads during this phase, allowing all threads to work more effectively in parallel.
+ struct ShenandoahRegionChunk assignment;
+ RememberedScanner* scanner = _heap->card_scan();
+
+ while (!_heap->check_cancelled_gc_and_yield(CONCURRENT) && _work_chunks->next(&assignment)) {
+ // Keep grabbing next work chunk to process until finished, or asked to yield
+ ShenandoahHeapRegion* r = assignment._r;
+ if (r->is_active() && !r->is_cset() && r->is_old()) {
+ HeapWord* start_of_range = r->bottom() + assignment._chunk_offset;
+ HeapWord* end_of_range = r->get_update_watermark();
+ if (end_of_range > start_of_range + assignment._chunk_size) {
+ end_of_range = start_of_range + assignment._chunk_size;
+ }
+
+ // Old region in a young cycle or mixed cycle.
+ if (is_mixed) {
+ // TODO: For mixed evac, consider building an old-gen remembered set that allows restricted updating
+ // within old-gen HeapRegions. This remembered set can be constructed by old-gen concurrent marking
+ // and augmented by card marking. For example, old-gen concurrent marking can remember for each old-gen
+ // card which other old-gen regions it refers to: none, one-other specifically, multiple-other non-specific.
+ // Update-references when _mixed_evac processess each old-gen memory range that has a traditional DIRTY
+ // card or if the "old-gen remembered set" indicates that this card holds pointers specifically to an
+ // old-gen region in the most recent collection set, or if this card holds pointers to other non-specific
+ // old-gen heap regions.
+
+ if (r->is_humongous()) {
+ if (start_of_range < end_of_range) {
+ // Need to examine both dirty and clean cards during mixed evac.
+ r->oop_iterate_humongous_slice(&cl, false, start_of_range, assignment._chunk_size, true);
+ }
+ } else {
+ // Since this is mixed evacuation, old regions that are candidates for collection have not been coalesced
+ // and filled. Use mark bits to find objects that need to be updated.
+ //
+ // Future TODO: establish a second remembered set to identify which old-gen regions point to other old-gen
+ // regions which are in the collection set for a particular mixed evacuation.
+ if (start_of_range < end_of_range) {
+ HeapWord* p = nullptr;
+ size_t card_index = scanner->card_index_for_addr(start_of_range);
+ // In case last object in my range spans boundary of my chunk, I may need to scan all the way to top()
+ ShenandoahObjectToOopBoundedClosure<T> objs(&cl, start_of_range, r->top());
+
+ // Any object that begins in a previous range is part of a different scanning assignment. Any object that
+ // starts after end_of_range is also not my responsibility. (Either allocated during evacuation, so does
+ // not hold pointers to from-space, or is beyond the range of my assigned work chunk.)
+
+ // Find the first object that begins in my range, if there is one.
+ p = start_of_range;
+ oop obj = cast_to_oop(p);
+ HeapWord* tams = ctx->top_at_mark_start(r);
+ if (p >= tams) {
+ // We cannot use ctx->is_marked(obj) to test whether an object begins at this address. Instead,
+ // we need to use the remembered set crossing map to advance p to the first object that starts
+ // within the enclosing card.
+
+ while (true) {
+ HeapWord* first_object = scanner->first_object_in_card(card_index);
+ if (first_object != nullptr) {
+ p = first_object;
+ break;
+ } else if (scanner->addr_for_card_index(card_index + 1) < end_of_range) {
+ card_index++;
+ } else {
+ // Force the loop that follows to immediately terminate.
+ p = end_of_range;
+ break;
+ }
+ }
+ obj = cast_to_oop(p);
+ // Note: p may be >= end_of_range
+ } else if (!ctx->is_marked(obj)) {
+ p = ctx->get_next_marked_addr(p, tams);
+ obj = cast_to_oop(p);
+ // If there are no more marked objects before tams, this returns tams.
+ // Note that tams is either >= end_of_range, or tams is the start of an object that is marked.
+ }
+ while (p < end_of_range) {
+ // p is known to point to the beginning of marked object obj
+ objs.do_object(obj);
+ HeapWord* prev_p = p;
+ p += obj->size();
+ if (p < tams) {
+ p = ctx->get_next_marked_addr(p, tams);
+ // If there are no more marked objects before tams, this returns tams. Note that tams is
+ // either >= end_of_range, or tams is the start of an object that is marked.
+ }
+ assert(p != prev_p, "Lack of forward progress");
+ obj = cast_to_oop(p);
+ }
+ }
+ }
+ } else {
+ // This is a young evac..
+ if (start_of_range < end_of_range) {
+ size_t cluster_size =
+ CardTable::card_size_in_words() * ShenandoahCardCluster<ShenandoahDirectCardMarkRememberedSet>::CardsPerCluster;
+ size_t clusters = assignment._chunk_size / cluster_size;
+ assert(clusters * cluster_size == assignment._chunk_size, "Chunk assignment must align on cluster boundaries");
+ scanner->process_region_slice(r, assignment._chunk_offset, clusters, end_of_range, &cl, true, worker_id);
+ }
+ }
+ if (ShenandoahPacing && (start_of_range < end_of_range)) {
+ _heap->pacer()->report_updaterefs(pointer_delta(end_of_range, start_of_range));
+ }
+ }
+ }
+ }
}
};
void ShenandoahHeap::update_heap_references(bool concurrent) {
assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
+ uint nworkers = workers()->active_workers();
+ ShenandoahRegionChunkIterator work_list(nworkers);
if (concurrent) {
- ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
+ ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator, &work_list);
workers()->run_task(&task);
} else {
- ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
+ ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator, &work_list);
workers()->run_task(&task);
}
+ if (ShenandoahEnableCardStats && card_scan()!=nullptr) { // generational check proxy
+ card_scan()->log_card_stats(nworkers, CARD_STAT_UPDATE_REFS);
+ }
}
-
class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
private:
+ ShenandoahMarkingContext* _ctx;
ShenandoahHeapLock* const _lock;
+ bool _is_generational;
public:
- ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
+ ShenandoahFinalUpdateRefsUpdateRegionStateClosure(
+ ShenandoahMarkingContext* ctx) : _ctx(ctx), _lock(ShenandoahHeap::heap()->lock()),
+ _is_generational(ShenandoahHeap::heap()->mode()->is_generational()) { }
void heap_region_do(ShenandoahHeapRegion* r) {
+
+ // Maintenance of region age must follow evacuation in order to account for evacuation allocations within survivor
+ // regions. We consult region age during the subsequent evacuation to determine whether certain objects need to
+ // be promoted.
+ if (_is_generational && r->is_young() && r->is_active()) {
+ HeapWord *tams = _ctx->top_at_mark_start(r);
+ HeapWord *top = r->top();
+
+ // Allocations move the watermark when top moves. However compacting
+ // objects will sometimes lower top beneath the watermark, after which,
+ // attempts to read the watermark will assert out (watermark should not be
+ // higher than top).
+ if (top > tams) {
+ // There have been allocations in this region since the start of the cycle.
+ // Any objects new to this region must not assimilate elevated age.
+ r->reset_age();
+ } else if (ShenandoahHeap::heap()->is_aging_cycle()) {
+ r->increment_age();
+ }
+ }
+
// Drop unnecessary "pinned" state from regions that does not have CP marks
// anymore, as this would allow trashing them.
-
if (r->is_active()) {
if (r->is_pinned()) {
if (r->pin_count() == 0) {
ShenandoahHeapLocker locker(_lock);
r->make_unpinned();
{
ShenandoahGCPhase phase(concurrent ?
ShenandoahPhaseTimings::final_update_refs_update_region_states :
ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
- ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
+ ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl (active_generation()->complete_marking_context());
parallel_heap_region_iterate(&cl);
assert_pinned_region_status();
}
trash_cset_regions();
}
}
void ShenandoahHeap::rebuild_free_set(bool concurrent) {
- {
- ShenandoahGCPhase phase(concurrent ?
- ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
- ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
- ShenandoahHeapLocker locker(lock());
- _free_set->rebuild();
+ ShenandoahGCPhase phase(concurrent ?
+ ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
+ ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
+ size_t region_size_bytes = ShenandoahHeapRegion::region_size_bytes();
+ ShenandoahHeapLocker locker(lock());
+ size_t young_cset_regions, old_cset_regions;
+ _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions);
+
+ if (mode()->is_generational()) {
+ assert(verify_generation_usage(true, old_generation()->used_regions(),
+ old_generation()->used(), old_generation()->get_humongous_waste(),
+ true, young_generation()->used_regions(),
+ young_generation()->used(), young_generation()->get_humongous_waste()),
+ "Generation accounts are inaccurate");
+
+ // The computation of bytes_of_allocation_runway_before_gc_trigger is quite conservative so consider all of this
+ // available for transfer to old. Note that transfer of humongous regions does not impact available.
+ size_t allocation_runway = young_heuristics()->bytes_of_allocation_runway_before_gc_trigger(young_cset_regions);
+ adjust_generation_sizes_for_next_cycle(allocation_runway, young_cset_regions, old_cset_regions);
+
+ // Total old_available may have been expanded to hold anticipated promotions. We trigger if the fragmented available
+ // memory represents more than 16 regions worth of data. Note that fragmentation may increase when we promote regular
+ // regions in place when many of these regular regions have an abundant amount of available memory within them. Fragmentation
+ // will decrease as promote-by-copy consumes the available memory within these partially consumed regions.
+ //
+ // We consider old-gen to have excessive fragmentation if more than 12.5% of old-gen is free memory that resides
+ // within partially consumed regions of memory.
+ }
+ // Rebuild free set based on adjusted generation sizes.
+ _free_set->rebuild(young_cset_regions, old_cset_regions);
+
+ if (mode()->is_generational()) {
+ size_t old_available = old_generation()->available();
+ size_t old_unaffiliated_available = old_generation()->free_unaffiliated_regions() * region_size_bytes;
+ size_t old_fragmented_available;
+ assert(old_available >= old_unaffiliated_available, "unaffiliated available is a subset of total available");
+ old_fragmented_available = old_available - old_unaffiliated_available;
+
+ size_t old_capacity = old_generation()->max_capacity();
+ size_t heap_capacity = capacity();
+ if ((old_capacity > heap_capacity / 8) && (old_fragmented_available > old_capacity / 8)) {
+ old_heuristics()->trigger_old_is_fragmented();
+ }
+
+ size_t old_used = old_generation()->used() + old_generation()->get_humongous_waste();
+ size_t trigger_threshold = old_generation()->usage_trigger_threshold();
+ // Detects unsigned arithmetic underflow
+ assert(old_used <= capacity(),
+ "Old used (" SIZE_FORMAT ", " SIZE_FORMAT") must not be more than heap capacity (" SIZE_FORMAT ")",
+ old_generation()->used(), old_generation()->get_humongous_waste(), capacity());
+
+ if (old_used > trigger_threshold) {
+ old_heuristics()->trigger_old_has_grown();
+ }
}
}
void ShenandoahHeap::print_extended_on(outputStream *st) const {
print_on(st);
bool ShenandoahHeap::should_inject_alloc_failure() {
return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
}
void ShenandoahHeap::initialize_serviceability() {
- _memory_pool = new ShenandoahMemoryPool(this);
- _cycle_memory_manager.add_pool(_memory_pool);
- _stw_memory_manager.add_pool(_memory_pool);
+ if (mode()->is_generational()) {
+ _young_gen_memory_pool = new ShenandoahYoungGenMemoryPool(this);
+ _old_gen_memory_pool = new ShenandoahOldGenMemoryPool(this);
+ _cycle_memory_manager.add_pool(_young_gen_memory_pool);
+ _cycle_memory_manager.add_pool(_old_gen_memory_pool);
+ _stw_memory_manager.add_pool(_young_gen_memory_pool);
+ _stw_memory_manager.add_pool(_old_gen_memory_pool);
+ } else {
+ _memory_pool = new ShenandoahMemoryPool(this);
+ _cycle_memory_manager.add_pool(_memory_pool);
+ _stw_memory_manager.add_pool(_memory_pool);
+ }
}
GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
GrowableArray<GCMemoryManager*> memory_managers(2);
memory_managers.append(&_cycle_memory_manager);
return memory_managers;
}
GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
GrowableArray<MemoryPool*> memory_pools(1);
- memory_pools.append(_memory_pool);
+ if (mode()->is_generational()) {
+ memory_pools.append(_young_gen_memory_pool);
+ memory_pools.append(_old_gen_memory_pool);
+ } else {
+ memory_pools.append(_memory_pool);
+ }
return memory_pools;
}
MemoryUsage ShenandoahHeap::memory_usage() {
- return _memory_pool->get_memory_usage();
+ return MemoryUsage(_initial_size, used(), committed(), max_capacity());
}
ShenandoahRegionIterator::ShenandoahRegionIterator() :
_heap(ShenandoahHeap::heap()),
_index(0) {}
void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
assert(worker_id < _max_workers, "sanity");
assert(_liveness_cache != nullptr, "sanity");
ShenandoahLiveData* ld = _liveness_cache[worker_id];
+
for (uint i = 0; i < num_regions(); i++) {
ShenandoahLiveData live = ld[i];
if (live > 0) {
ShenandoahHeapRegion* r = get_region(i);
r->increase_live_data_gc_words(live);
return true;
}
return false;
}
+
+ void ShenandoahHeap::transfer_old_pointers_from_satb() {
+ _old_generation->transfer_pointers_from_satb();
+ }
+
+ template<>
+ void ShenandoahGenerationRegionClosure<YOUNG>::heap_region_do(ShenandoahHeapRegion* region) {
+ // Visit young and free regions
+ if (!region->is_old()) {
+ _cl->heap_region_do(region);
+ }
+ }
+
+ template<>
+ void ShenandoahGenerationRegionClosure<OLD>::heap_region_do(ShenandoahHeapRegion* region) {
+ // Visit old and free regions
+ if (!region->is_young()) {
+ _cl->heap_region_do(region);
+ }
+ }
+
+ template<>
+ void ShenandoahGenerationRegionClosure<GLOBAL_GEN>::heap_region_do(ShenandoahHeapRegion* region) {
+ _cl->heap_region_do(region);
+ }
+
+ template<>
+ void ShenandoahGenerationRegionClosure<GLOBAL_NON_GEN>::heap_region_do(ShenandoahHeapRegion* region) {
+ _cl->heap_region_do(region);
+ }
+
+ bool ShenandoahHeap::verify_generation_usage(bool verify_old, size_t old_regions, size_t old_bytes, size_t old_waste,
+ bool verify_young, size_t young_regions, size_t young_bytes, size_t young_waste) {
+ size_t tally_old_regions = 0;
+ size_t tally_old_bytes = 0;
+ size_t tally_old_waste = 0;
+ size_t tally_young_regions = 0;
+ size_t tally_young_bytes = 0;
+ size_t tally_young_waste = 0;
+
+ shenandoah_assert_heaplocked_or_safepoint();
+ for (size_t i = 0; i < num_regions(); i++) {
+ ShenandoahHeapRegion* r = get_region(i);
+ if (r->is_old()) {
+ tally_old_regions++;
+ tally_old_bytes += r->used();
+ if (r->is_humongous()) {
+ ShenandoahHeapRegion* start = r->humongous_start_region();
+ HeapWord* obj_addr = start->bottom();
+ oop obj = cast_to_oop(obj_addr);
+ size_t word_size = obj->size();
+ HeapWord* end_addr = obj_addr + word_size;
+ if (end_addr <= r->end()) {
+ tally_old_waste += (r->end() - end_addr) * HeapWordSize;
+ }
+ }
+ } else if (r->is_young()) {
+ tally_young_regions++;
+ tally_young_bytes += r->used();
+ if (r->is_humongous()) {
+ ShenandoahHeapRegion* start = r->humongous_start_region();
+ HeapWord* obj_addr = start->bottom();
+ oop obj = cast_to_oop(obj_addr);
+ size_t word_size = obj->size();
+ HeapWord* end_addr = obj_addr + word_size;
+ if (end_addr <= r->end()) {
+ tally_young_waste += (r->end() - end_addr) * HeapWordSize;
+ }
+ }
+ }
+ }
+ if (verify_young &&
+ ((young_regions != tally_young_regions) || (young_bytes != tally_young_bytes) || (young_waste != tally_young_waste))) {
+ return false;
+ } else if (verify_old &&
+ ((old_regions != tally_old_regions) || (old_bytes != tally_old_bytes) || (old_waste != tally_old_waste))) {
+ return false;
+ } else {
+ return true;
+ }
+ }
+
+ ShenandoahGeneration* ShenandoahHeap::generation_for(ShenandoahAffiliation affiliation) const {
+ if (!mode()->is_generational()) {
+ return global_generation();
+ } else if (affiliation == YOUNG_GENERATION) {
+ return young_generation();
+ } else if (affiliation == OLD_GENERATION) {
+ return old_generation();
+ }
+
+ ShouldNotReachHere();
+ return nullptr;
+ }
+
+ void ShenandoahHeap::log_heap_status(const char* msg) const {
+ if (mode()->is_generational()) {
+ young_generation()->log_status(msg);
+ old_generation()->log_status(msg);
+ } else {
+ global_generation()->log_status(msg);
+ }
+ }
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